California Code, Government Code - GOV § 31648.5

Any elective officer (a) who has filed a declaration of election to become a member of a county retirement association established pursuant to this chapter and (b) who rendered any county service after the effective date of the system so established and prior to the effective date of his membership in the association and (c) who would not otherwise be entitled to credit for such service, shall be entitled to credit for such service as current service if he contributes to the retirement association the contributions which he would have made if he had been a member of the association during the time such service was rendered, together with regular interest thereon.